What are good default key mappings for action games, the kind that uses a handful of buttons plus directional controls?

In the DOS/Amiga days, most of these games used modifier keys because these were less likely to be jammed/ghosted. This fell out of use because Microsoft added the Win key which is easy to accidentally press.

But I'm not sure what's a good default these days. Japanese indie games often use the ZXCV group, although I understand this is a problem for German keyboards with their swapped Z and Y (but there's a solution for that: use scancodes). Some other indie games use this group too, like Risk of Rain and Spelunky.Other games use the left home keys, possibly influenced by MOBAs. FEZ uses the modifier keys plus WSAD for all its controls. Treasure Adventure game uses ASZX, a hybrid of the two.